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G. A. YANOCHOWSKI AND H. E. HERSHEY- TELEPHONE SYSTEM.

APPLICATWN FILED AUG.2I, 1918.

Patented Aug. 26, 1919.

3 SHEETS-SHEET I.

[mien UI"5.- George H.Y5HDUZ7UIn/5kl &

Harry Pal-15y.

G. A. Y*ANOCHOWSKI AND H. E. HERSHEY.

TELEPHONE SYSTEM.

APPLICATION FILED AUG-2|. 1918.

Patented Aug. 26, 1919.

[I'LL/EH UPS w w b 5 we V H m 5 mH e E HIT.

G. A. YANOCHOWSKIAND H. E. HERSHEY.

TELEPHONE SYSTEM.-

APPLICATION FILED AUG.2I. ms.

1 ,3 1 4,453 I Patented Aug. 26,-1919.

3 SHEETS-SHEET 3.

Harry flfiershsg GEORGE A. YA'NOCHOWSKI, OF CHICAGO, ILLINOIS, AND eWHITE WATER, KANSAS, ASSIGNOES T0 AUTOMATIC ELE t E. nansm, or me companor CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Patented Aug. 26, 1919.

original application filed December 5, 1913, Serial No. 804,894. PatentNo 1,278,282, dated September 10, 1918. Divided and this applicationfiled August 21, 1918. Serial No. 250,858.

To all whom it may concern:

Be it known that we, GEORGE A. YANO- onowsm and HARRY E. HERSHEY, bothcitizens of the United States of America, and residents of Chicago, Cookcounty, Illinois, and White Water, Butler county, Kansas, respectively,have invented certain new and useful Im rovements in Telephone Systems,of which t hc following is a specification.

Our invention relates to improvements in telephone systems, and itrelates particularly to improved means for operating measured servicedevices or supervisory signals in an automatic or semi-automatic systern.

The object of our invention is to provide, in connection with atelephone system, a simplex circuitthat is, a circuit which includes twosides of the line in multiple with a ground return-Which circuit may beemployed for either operating meters or paystation apparatus inautomatic systems, or can be employed for supervisory purposes insemi-automatic systems. In these systems the talking current andoperating impulses pass over the two sides of the line in series andthus the impulse or impulses which pass over the simplex circuit do notin any way interfere with the talking current or operating impulses.

A further feature of our invention is the provision of a time-controlledmechanism associated with the simplex circuit for closing the same .atpredetermined time intervals, whereby a measured service device at thesubstation may be operated a number of times in accordance with thelength of time any connection is established. Thus this timingmechanismcan be regulated so as to operate every few seconds, and inthat event the registering mechanism at the substation will accuratelyrecord the exact length of time of conversation and charges can be madeaccordingly, or, if desired, this timing mechanism can be so regulatedas to close the simplex circuit once every three minutes, in which eventthe subscribers meter would be operated one step for every three minutes'a connection is established.

This application is a division of our Patent No. 1,278,282, issuedSeptember 10, 1918. The feature which we desire to patent in thisdivision is that of a supervisory or other signal operated over asimplex circuit, such a signal being shown in Figure 4 of the drawings.

These and other objects and features of our invention will be moreclearly understood by reference to the accompanying drawings, in whichwe have illustrated our invention in connection with automatic andmanual apparatus of well-known types although 1ts application to otherforms 0 automatic and semi-automatic s stems will be readily apparent tothose skllled in the art Fig. 1 shows a subscribers substation Aattached to a party-line, the line conductors of said party-lineterminating in n individual or line switch C. The line switch shown at Cis one of a grou of similar line switches the plungers (not s own) ofwhich engage a shaft and are controlled by the operation of a masterswitch, shown at D in such a manner that the are, when in normalposition, held directly in front of the terminals of a trunk lineleading to a selector such as shown at E.

Fig. 2 shows a connector switch embodying the principles of ourinvention.

'Fig. 3 shows a second connector switch. adapted to be used inconnection with our invention.

Fig. t shows a manual operators cord circuit for connectin a trunk lineextending from the selector with a trunk line extending to the connectorJ (Fig. 5).

Fig. 5 shows a subscribers substation A, together with a line switch Cwith which a connector J is shown connected.

For the purpose of supplying battery current for operating the apparatusand for talking purposes, there is shown a battery B, one terminal ofwhich is grounded. The busy signaling machines Q, Q and Q as representedherein, comprise an induction coil or transformer, the prima winding ofwhich is included in a local clrcuit with a battery and an interrupter.Through the medium of this interrupter interrupted current is suppliedto the rimary winding, which induces an alternating current in thesecondary winding, whereby when said winding is connected with asubscribers line, a buzzing sound is heard in the re- The automatictelephone or substation represented at A comprises the usual receiver 2,transmitter 3, ringer 4 and condenser 5. Be-

.ing an automatic substation. it is also pro 5 Vided with an automaticcalling device which ma be of the same type as that shown in Britishpatent to S. G. S. Dicker No. 29,654

of 1910. At the substation A the calling device is showndiagrammatically by a pair of to im 'ulse springs 6 and 7 and a toothed1mpu se wheel 8, which latter is controlled by the subscriber throughthe medium of a dial (not shown) provided with finger holes forconvenience in turning. The switch-hook 9 16 controls a set of springsin such a manner that when the receiver is on the hook, the ringer 4 inseries with the condenser 1s bridged directly across the line, bothsldes of sa1d line being opened beyond saidbridge.

20 When the receiver is removed from the hook,

the springs assume a position in which the.

bridge above referred to is disengaged from one side of the line, and atthe same time the receiver 2 is bridged across the line in series withthe impulse springs 6'and 7 and the transmitter 3. An impedance coil 12is also bridged across the line anda magnet 10 is connected'between themidpoint of this impedance coil and ground G The armature of this magnet10 is designed to operate a counting or registering mechanism each time"the magnet is energized. The impulse wheel 8 controls a set ofspringsin such a manner that when it is at any other position but'normal, theimpedance coil 12 is disen- N gaged from both sides of the line. Forthis reason it will be seen that the impedance coil 12 will not aflectthe impulses delivered by the impulse springs 6 and 7 .The substatlon Ais similar to the substation A, except that the magnet 10', instead ofoperating a counting mechanism, is arranged to control a set of springsin such a manner that when the magnet 10 is energiz'ed, a shunt isplaced around the receiver 2' and the transmitter 3 is directly short- Icircuited. Means are also provided so that when a proper coin is droppedin the slot,

the said sprin are restored to normal.

The subscri ers individual switch C is of the general type ofsubscribers switch shown in British patent to R. W. James No. 26,301 of1906, being, however, of the particular type disclosed in British patentto T. G. Martin No. 1419 of 1910. This line switch comprises, amongother details, a plunger (not shown) attached to the end of a socalledplunger arm 27 which is controlled by the magnet 170. The magnet 170com- -prises four windings, namely, a pull-down 4 winding 25. a cut-0Eor holding winding 39,

a line winding 11 and an auxiliary winding 26. The core of the magnet170 is so constructed that the magnetic circuit of the windings 25 and39 is separated from that of granted March 13, 1906, to Keith, Ericksonthe windings l1 and 26. The winding 25 opcrates both the plunger arm 27and the armature 36, whilethe winding 39 is only strong enough to ocrate the cut-0H armature 36 and to hol the plunger arm 27 in itsoperated position. When the plunger arm 27 is operated, the plunger-isforced into a bank of contact springs, forcing the springs 28, 29, 30and 31 into engagement with the springs 32, 33, 34 and 35,respectively.Although only one set of springs (28 and 35) is shown, each line switchis provided with a plurality of such sets, each set forming the'terminalor a trunk line leading to-a first-selector switch E. Each trunk line isconnected in multiple with the corresponding springs of all the lineswitches I of the group which is controlled by the master switch D. Theswitch D is controlled by the subscriber through the medium of the linerelay 11, as will hereinafter be more fully explained.

The master switch D is of the same general type as that disclosed inBritish Patent No. 26,301 of 1906, referred to above, being, however, ofthe particular type disclosed in said BritishPatent No. 1419 of 1910.The function of the master switch, as is well known, is to maintain theplungers of all idle switches in position to engage the ter" minals ofan idle trunk line.

The first selector switch E is of the general type, of selector switchdisclosed in- United States Letters Patent No. 815,321,

and Erickson, except that the so-called side switch is omitted, and itscircuits are medi fied to adapt the switch to operate in a system inwhich the impulses are delivered over the sides of-the line in series.Among other details, the selector E comprises a bank of contactsarranged in horizontal rows or levels, which contacts are adapted to beengaged by a set of wipers 65, 66 and 67 carried upon a shaft (notshown) which has a 11( vertical movement controlled by the verticalmagnet 50 and a rotary motion controlled by the rotary magnet 51. Theoperations of the switch are controlled through the medium of thedouble-wound line relay 40. Means for permittingthe switch to berestored to normal position are provided in the release magnet1.21,which, upon energizing, withdraws the retaining pawls from theshaft. The springs 61 and are permitted 120 to close only when theswitch shaft has been raised one or more steps from its lowest position.The relays 45'and'56 are slow acting relays, i. 6., they denergizeslowly after their energizing circuits are broken.

The connector switch I (Fig. 2) is of the general type of connectorswitch disclosed in United States Letters Patent No. 815,17 6, p grantedMarch 13, 1906, to Keith, Erickson and Erickson, the circuits beingmodified,

however, to adapt the switch to operate in a system in which theimpulses are delivered over the two sides of the line in series.

' ner. The magnet 118 is the usual release magnet which, uponenergizing, removes the retaining pawls rom the shaft. The springs .117and 127 are permitted to close only when the switch shaft has beenraised one or more steps from its lowest position. The operations of theswitch are controlled by the line relay 70, and the application ofringing current to the called lme is controlled by the 'rin er relay101. The relay 103 is the socal ed back-brid e relay which feeds batterycurrent to t e called line. This relay controls the 'circuit'of a pairof impedance coils which are adapted to be connected in bridge of thetrunk line 71, 76. The battery B is adapted to be connected to thisbridge, which battery connection is controlled by the slow acting relay108, which in turn is controlled by the ring-cut-ofi relay 104 in such amanner that battery is connected to this bridge for a short interval oftime when the subscriber responds, in a manner to be hereinafter morefully described.

The connector K (Fig. 3) is similar to the connector I (Fig. 2), exceptfor the fact that the relay 208, which controls the bridge through theimpedance coils 209 and 213, which correspond in turn to the impedancecoils 109 and 113 of the connector I, is controlled by a time mechanismM. This convstruction is such that the simplex circuit through the coils209 and 213 in parallel is closed intermittently by this time mechanisminstead of being closed but a single time, as described in connectionwith the connector I.

' The connector J is similar to the connector I, except that in place ofthe im edance coils 109 and 113 and the relay 108, t is connector T isprovided with a relay 309 whose circuit 18 controlled by the back-bridgerelay 303, which relay 309 in turn controls the circuit of the impedancecoil 313. This construction is such that-when the back-bridge"relay isenergized, the relay 309 and impedance coil 313 are bridged across theconductors of the talking circuit-and the battery B is connected to amid point of this bridge and remains so connected until the back-bridgerelay deenergizes, in this manner distinguishin from the construction ofthe connectors and K, in which the battery was connected to this bridgeonly momentarily.

The cord circuit G (Fig. 4) is a wellknown type of cord circuit,comprising the usual answering and calling plugs P and P, respectively,inductively connected together through the medium of the condensers 159and 174. The usual supervisory lamps 157 and 160 are controlled by thewell-known plug seat switches shown at 156, and 158. The key L is alistening key for connecting the operators talking set with the cord G.The key L is a calling device key, the purpose of which is to connect acalling device with the cord circuit, through the medium of which theoperator may control the automatic switches. to'set up the properconnection. The calling device may be of "any desired ,type, such, forinstance, as that shown in British Patent No. 29,654 of 1910, abovereferred to, through the medium of which calling device the operator mayinterrupt the bridge across the trunk line a desired nmnber of times foreach of the digits of the number of the called subscriber Having given ageneral description of the apparatus, it will now be explained how asubscriber, such as the subscriber A, may establish connection withvarious subscribers who are accessible, first, through the connector Iand then through the connector K. The connector I, for example, can beconsidered one which has access to local sub scribers, as whenconnection is made through this connector, the meter of the callingsubscribers line is operated but a single time for each call. Theconnector K can be considered one which has access to subscribers at amore distant point, and when connection is established through suchconnector, the subscribers meter is operated once for everypredetermined period during which the connection is established.

Since the automatic switching apparatus disclosed is of a well-knowntype and is in general well known in the art, and is fully described inthe patents and publications referred to, it is not thought necessary todescribe the operations in detail, but their operations will bedescribed in a more or less general manner.

When the subscriber at substation A removes his receiver from theswitch-hook preparatory to making a call, the line winding 11 of theline switch C is closed in the well-known manner, and this line switchis then operated to connect with an idle trunk line extending to theselector E. This operation is well understood and is fully described inthe British patents referred to, and it is accordingly thoughtunnecessary to describe its operation further. Upon this line switchseizing an idle trunk line, which we will assume to be the trunk line32, 35, the line relay 40 of the selector E is energized over thefollowing circuit: from ound through the lower half of the line relay40, springs 41 and 42 of the relay 68, springs 35 and 31, line conductor15, springs 16 and 17 at the substation A, receiver '2, impulse springs6 and 7 transmitter 3, springs 18 and 19, line conductor 20, springs 28and 32, springs 43 and 44 of the relay 68 and the upper winding of theline relay 40 to bat tery B. A branch circuit at the substation A isformed from the "spring 17 through the springs 23, impedance coil 12 andthe springs 24. to the spring 18. A circuit may also be traced fromground G through the relay 10, left-hand half of the impedance coil 12,springs 24, springs 18 and 19, line conductor 20, springs 28 and 32,springs 43. and 44 of the relay 68 and the upper winding ofthe Qrelay 40to battery B. The resistance of this circuit is sufiicient to preventthe relay 10 from bperatively energizingat this time. The line relay 40,upon becoming energized over, the above circuits, closes a circuitthrough the relay 45 from ground G through the springs 46 and 47 and therelay 45 to battery B. The relay 45, upon becoming energized, forms theholding circuit for the switch C, which circuit extends from ground Gthrough the springs 48, springs 33 and 29 and the holding winding 39 'tobattery B. The winding 39, upon energizing, holds the armature 36 andthe plunger arm 27 in their operated positions after the circuit of thepull-in winding 25 is broken by the falling back of the armature 37.From the spring 29 a guarding potential is extended by the conductor 49to the private bank contacts associated with the line switch 70. Theenergization of the relay 45 also p prepares 'a circuit for the verticalmagnet 50 by bringing into engagement the springs 54 and 55 and opensthe circuit of the release ma et 121 at the springs 54 and 119.

he calling subscriber now operates his calling device for-the firstdigit 2 of the called number. It will readily be seen that the impedancecoil 12, which was heretofore bridged across theline, is cut ofi at thesprings 23 and the springs 24 at the instant that the dial is rotated bythe subscriber,

and that said impedance coil will not again ter relay deenergizes, animpulse is trans mitted over a circuit extending from ground Gr throughthe springs 46and 52, springs 53, springs 54- and 55, relay 56 and thevertical magnet 50 tobattery B. The vertical magnet receives twoimpulses over this circuit and operates :to raise the switch shaft andwipers two steps to a position opposite the contact which it engagesprovided with arge-ea the second row or level of bank contacts...

The slow acting relay 56 is maintained in its energized positioncontinuously while immagnet through it and in its energizedpositioncloses a circult extending from ground G through the springs 57 and 58-and the relay 59 to battery B. The relay 59, upon energizing, forms alocking circuit for itself extending from ground G through the springs48, springs 60,0fi-n0rnialspr1ngs 61, springs 62 and 63 and the relay 59to battery B. Thus upon the deenergization of the relay '56 after thelast impulse is delivered to the vertical magnet, the relay 59 remainsenergized and the circuit of the rotary magnet 51 is closed, whichcircuit extends from ground G through the springs p If the first-trunkline of the second level is idle, the relay 59 deencrgizes as soon asthe springs 60 are opened. If this trunk line is busy, however, theprivate wiper 66 finds a' guarding" ground potential which'istransmitted through the springs 62 and 63 of the relay 59 and reventsthe relay 59 -from denergizing. T e magnet 51, however, de-

regardless of whether or not the relay 59 energizes when the springs 64are broken,

remains energized. If the relay 59 remains energized, the circuit oftherotary magnet will be again closed as soon as its armature drops backfar enough to close the springs 64. The rotary magnet will, therefore,operate in a manner similar to that of a buzzer to advance the wipersstep by step over the contacts until the non-grounded contact of an idletrunk is reached by the Wiper 66, whereupon the relay 59 deenergizes.The relay 59, upon deenergizing, whether after. one or severaloperations of the rotary magnet, permanently breaks the circuit of saidrotary magnet and closes the circuit of the 1 switching relay 68, whichcircuit extends from ground G through the springs 48, springs 60,olf-normal springs 61, springs 62 and 69 and the relay 68 to battery B.

The relay 68, upon energizing, disconnects 120 the line relay 40 fromthe line and extends the line connection through the wipers 65 and 67 tothe connector I; The line relay 70 of the connector I becomes energizedover a circuit extending from ground G through 1 5 the lower winding ofthe relay 70, conductor 71, bank contact 72, line wiper 67, springs 73and 42 of the relay 68, springs 35 and 31, line conductor '15, springs16 and 17 of the substation A, receiver 2, impulse springs 6 39 contact75, conductor 76 and the upper winding of the line relay 70 to batteryB. At the substation A a branch circuit is formed from the spring 17through the springs 23,

impedance coil 12 and the springs 24 to the springs 18. A circuit mayalso be traced from ground G through the relay 10, lefthand half of theimpedance coil 12, springs 24, springs 18 and 19, line conductor 20,springs 28 and 32, springs 43 and 74 of the relay 68, line wiper 65,bank contact 75, conductor 76 and the upper winding of the line relay 70to battery B. The resistance of this circuit is suflicient to preventthe relay 10 from operatively energizing at this time. The energizationof the line relay 7 0 closes a circuit through the relay 77 from groundG through the springs 78 and 79 and the relay 77 to battery B. Theenergization of the relay 77 afi'ords a new holding ground for the relay68 of the selector E and the holding winding 39 of the line switch C totake the place of ground G which is removed upon the denergization ofthe relay 45. This holding circuit extends from ground G through thesprings 80, conductor 81, bank contact 82, private wiper 66, springs 62and 69 and the relay 68 to battery B. A branch of this circuit alsoextends from the private wiper 66 through the offnormal springs 61,springs 60, springs 33 and 29 and the holding coil 39 to battery B. Fromthe spring 29 the conductor 49 carries the guarding potential to theconnector private bank contacts associated with the line switch C. Theenergization of the relay 77 also prepares the circuit of the verticalmag- .net 87 at the springs 84 and 85 and opens the circuit of therelease magnet 118 at the springs 84 and 116. When the substationcalling device is operated for the second digit 2, the circuit of theconnector line relay is broken twice. Since the relay 77 is slow actingit does not deenergize during the momentary interruptions of its circuitby the line relay 70, so that each time the latter relay is deenergized,a circuit is closed extending from ground Gr through the springs 7 8 and83, springs 84 and 85, relay 86, vertical ma et 87 and the side switchwiper (in first position) to battery B. The vertical magnet receives twoimpulses over this circuit and operates to raise the switch shaft andwipers 89, 90 and 91 to a position opposite the second level of bankcontacts. The relay 86, which is included in the operatin circuit of thevertical magnet, remains in its energized position during the entiretime that impulses are being transmitted throu h it and operates toclose the circuit of t e private magnet 94 from ground G through thesprings 92 and 93 and the private magnet 94 to battery B. After the lastimpulse has been delivered, the relay 86 opens the circuit of theprivate magnet 94, which, upon deenergizing, permits the side switch topass from first to second position. The movement of the side switchwiper 88 from first to second position transfers the battery connectionfrom the vertical magnet to the rotary magnet.

The calling subscriber now operates his calling device for the lastdigit 2, in response to which the connector line relay 70 operates totransmit two impulses through the rotary magnet 96 in series with therelay 86 over a circuit extending from ground G8 through the springs 78and 83, springs 84 and 85,

relay 86, springs 95, rotary magnet 96 and the side switch wiper 88 (insecond position) to battery B. The rotary magnet thereupon rotates theshaft wipers onto the contacts of the called line, which called line wewill assume is similar to the line to which the substation A isconnected and is provided with a line switch similar to the switch C.The relay 86 operates in response to the impulses for this digit in thesame manner as for the previous digit to cause the private magnet 94 toadvance the side switch to third position. By the engagement of the sideswitch wipers 97 and 98 with their thirdposition contact points, theline connection is completed with the called line. Upon the engagementof the wiper 99 with its third position contact point, a circuit iscompleted through the cut-olf'winding of the called line switch. Thesaid circuitextends from ground G through the side switch wiper 99 (inthird position), private wiper 90 and the cut-off winding of the calledline switch to battery B. The cut-off winding of the called line switch,upon energizing, operates to disconnect the line relay from the calledsubstation. The connection of ground G with the connector bank contactof the called line prevents the called line from being seized by someother connector switch. By the engagement of the side switch wiper88with its third-position contact point, the circuit of the ringer relay101 is closed. This circuit extends from ground G12 through theinterrupter 100, ringer relay 101, springs 102 and the side switch wiper88 (in third position) to battery B. 'Ther'inger relay disconnects thecalling line from the called line and bridges the ringing currentgenerator R across the called line to signal the called subscriber. Theringer relay is energized only intermit' tently throu h the medium ofthe interrupter 100. Tlpon the response of the called subscriber hisline is provided with talking current through the windings of thebackbridge relay 103, which relay, upon energizing, closes a circuitthrough the ringer cut-off relay 104, the circuit extending from stantthat the side switch passes to third' position a circuit is closedthrough the slow acting relay 108 as follows: from ground G through theside switch wiper 99 (in third position), springs 107 and the relay 108to battery B. The relay 108, upon energizing, connects the coils 109 and113 in series and connects battery B with a point between them. Theback-bridge relay 103 being energized at this time, these coils 109 and113 are bridged across the conductors of the talking circuit. A circuitis therefore closed from battery B,'contact springs 115, 112 and 110,through the coils 109 and 113 in arallel,'thence over the two sides ofthe talking circuit in parallel to the calling substation A, thencethrough the coils 12 to their midpoint and then through the relay 10 toground Suflicient current flows over this parallel circuit to cause therelay 10 to energize and it therefore operates to advance the countingmechanism one step. It will be seen that when the ring-cut-ofi relay 104energizes, the circuit of the relay 108 is broken at the springs 107.The relay 108 is made slow acting. so that it may remain energized longenough to send an impulse of current over the simplex circuit sufiicientto operate the meter at the sub station A. Upon the deenergization ofthe I relay 108 the simplex circuit is broken at the springs 110, 11 2and 115 and the relay 10 at the substation Areturns to normal.

After the'conversation is completed, the connection is released by thehanging up of the receiver at the calling substation in the usual andwell-known manner, which it is not thought necessary to here describe indetail.

i been established with the called line.

nected with the calling If the called line had been busy when theconnector wipers landed on the bank "contacts of the called line, thenthe side switch would not' have passed to third position and connectiontherefore would not h iafie e busy machine Q. wouldal'so have beenconline, all in a manner wellunderstood in the art. The callingsubscriber, upon hearing the busy si nal, replaces the receiver upon thehooh, whereupon the switches are released in the regular manner. P p 0Should, now, the subscriber at substation A wish to establish connectionwith a line which is accessible from the connectorK.

(Fig. 3), he would proceed in the same manner as above outlined,'exceptthat'he would instead of 2, thereby raising the first selector to thethird level of bank contacts which are connected to a group ofconnectors, one

, of which is indicated at K. Upon the subscriber at the substation Acalling the last two digits of the called number, the action of theconnector K is the same as exrelay 203 becomes energized, due to thecalled subscriber removingv his receiver, the

coils 209 and 213 are connected one to each side of the calling line inthe same manner as is described in connection with the coils 109 and 113of the connector 1. Each time the mechanism M completes the circuit ofthe relay 208, the springs 210, 212, and 125 will be closed, thuscompleting the circuit between the coil 209 and the coil 213 and placingbattery B between them. As a result the relay 10' at the substation A isenergized over the simplex circuit and causes the counting mechanism toadvance one step for each impulse sent out from the mechanism M. In thisway the meter at the substation A will be operated in proportion to thelength of timethat the sub- .scriber at the substation *A converses withthe called subscriber, instead of being op erated but once, as inconnection with the connector I. d

If, now, the subscriber at the subtation A wishes to extend a connectionthrough the manual board L, he proceeds as heretofore described, exceptthat he operates his calling dial for a first digit 1, whereby the whichextend truck lines to the manual I boardL, each of which trunklines'includes station A, over the circuit previously traced and back tothe line wiper 65, through the bank contact 135, conductor 138, springs145 and 144 and the relay 146 to battery B.

-The relay 146, upon energizing, forms a holding circuit for therelay 68of the selector E and the holding winding 39 of the line switch C fromground G through the springs 147, conductor 139, bank contact 136,private wiper 66 and continuing over the circuit previously traced tobattery .B.

The energization of the relay 146 also closes a circuit throrgh the lamp149 as follows:.

from ground G through springs 148 and the lamp 149 to battery B. Theoperator, upon seeing the lamp 149 lighted, plugs into the jack N withthe answering plug P. The engagement of the sleeve of the plug P withthe bush of the jack N closes a circuit through the cut-off relay 150.The cut-0E relay, upon energizing, cuts ofi the relay 146 and the coil141 and extends the lines to the cord circuit G. A circuit may now betraced from ground G through the relay 151, ring of the plug P and ringspring of the jack N, springs 152 and 143, conductor 140 to and throughthe substation A, over the circuit previously traced and back to theconductor 138, springs 145 and 153, tip spring of the jack N and tip ofthe plug P and the coil 154 to battery B. The tip of the plug P alsoforces the springs 155 into engagement, which connects ground G" in theholding circuit for the relay 68 of the selector E and the holding coil39 of the line switch C before traced. The relay 146 is made slow actingso that ground G will not be removed until time has been given for theplug P to be forced clear into the jack N. When the plug P was removedfrom the plug seat switch 156, the lamp 157 was lighted. The lamp wentout, however, as soon as the relay 151 was energized. The operator willnow depress her listening key and converse with the subscriber at thesubstation A. Upon learning that he desires connection with thesubstation A, the number of which we will assume to be 22, the operatorremoves the plug P from the plug seat switch 158 and touches the tip ofsaid plug to the bush of the outgoing ack.

- If a multiple of the jack H be busy,

or should a selector have seized that trunk, the bush will have aguarding potential upon it which will give the operator a click in herreceiver when she places the tip of the plug P against the bush, due tothe discharge of the condenser 159. Assuming that the trunk to which thejack H is connected is idle, the operator then forces the plug P intothe jack H, which extends the line connection to the connector J overthe conductors 162 and 164. Immediately the connector J returns aguarding ground over the conductor 163 to the bush of the jack H. Uponremoving the plug P from the plug seat switch 158, the lam 160 islighted and remains lighted until t e called subscriber answers. Theoperator now operates the key L to bridge -her calling device 161 acrossthe conductors 162 and 164. She then operates her calling device for thedigit 2 twice, as a result of which the connector J operates to extendthe connection to the called substation exactly as explainedv in thedescription of the connector I. The operator now restores the key L tonormal, bringing the relay 165 across the conductors 162 and 164. Theresistance and construction of the relay 165 is such that it will notoperatively energize with the current received through the connectorline relay 370, although the said connector line relay is energized overthis circuit. When the back-bridge relay 303 energizes, due to thecalled subscriber removing his receiver, the relay 309, by means of thesprings 311, is placed between battery B and the conductor 162 inparallel with the upper winding of the relay 370. The relay 309immediately energizes and closes the springs 312. It will now be readilyseen that the relay 309 in series with the coil 313 is bridged acrossthe conductors 162 and 164 and that the battery B is connected to apoint between the relay 312 and the coil 313. As a result, current willflow from the ground G through bothwindings of the relay 165, both sidesof the line in parallel and the relay 309 in parallel with the coil 313to battery B. The relay 165 will be energized over the above circuit,thus opening the circuit of the lamp 160 at the springs 166. Theextinguishing of the lamp 166 notifies the operator that the calledsubscriber has answered, whereupon the operator depresses the key Lwhich sends an impulse through the impedance coil 167 over the simplexcircuit previously traced to operate the meter at the substation A.

When the conversation is completed and the calling subscriber hangs hisreceiver upon the switchhook, the circuit through the relay 151 isbroken. The relay 151, upon denergizing, again closes the circuit of thelamp 157. When the called subscriber replaces his receiver upon theswitchhook, the circuit of the back-bridge relay 303 is broken. Thedene'rgization of the relay 303 removes the relay 309 and the relay 313from across the line. This causes the relay 165 to deenergize and againlight the lamp 160. The operator, noticing the lamps Y157 and 160glowing, knows that the conversation has been completed and re moves thelugs P and P from their respective jac s N and H. The removal of theplug P takes ground from the relay 6.8 and the holding coil 39,whereupon the release of the selector E and the line switch C follows,in the manner well understood 4 in the art. The removal of the plug Pfrom the jack H likewise causes the connector J to release.

At the substation A (Fig. 5) we have shown a modified arrangement inwhich the magnet 10', instead of operating a registering or countingmechanism, as does the magnet 10 in Fig. 1, controls a coin-controlledmechanism. This magnet 10 is connected in the simplex circuit in thesame manner as isthe magnet 10, heretofore dewill be unable to conversewith him either through the transmitter or the receiver. Thereupon thesubscriber at the substation A deposits a coin in the slot, saidrcoincausing the arm 168-to be freed from. 'the armature 169. The freeing ofthe arm 168 re moves the shunt from the receiver 2 and the short-circuitfrom the transmitter 3 even though the relay 10' remains energized, thusallowing the subscribers to converse.

' It will thus be seen that we have devised a very eflicient system inwhich a simplex circuit can be employed for operating varying forms ofmeasured service devicesor for supervisory purposes. 'While for thepurpose'of illustration and to more fully describe the application ofour invention, we.

have shown the same in connection with automatic apparatus of well-knowntypes, it will readily be apparent to those skilled in the art that ourinvention is equally as well adapted for use in connection with manyother forms of' an automatic apparatus. Likewise, the particular form ofmanual apparatus shown in Fig. 4 could be modified to suit varyingrequirements.

What we claim as our invention is;

1. In a telephone system, a plurality of normally disconnectedsubscribers lines, au-

tomatic switches for establishing a talking circuit between said lines,said talking circuit including a pair of talking conductors, meanscontrolled by the response of the called subscriber for closing acircuit including. the two sides of said talking circuit in parallelanda signal controlled over said circuit. p l

2. In a telephone system, a plurality of normally disconnectedsubscribers lines, au-

ena ass 3. In a telephone system, a plurality of normally disconnectedsubscribers" lines,

means for establishing connection between two of said lines, a bridgeacross the calling line, a magnet in series with said bridge, a secondbridge adapted to be placed across the conductors of the talkingcircuit, means controlled by the response of the called sub-- scriberfor automatically connecting battery to the mid-point of said secondbridge to thereby energize said magnet, and a signal controlled by saidmagnet.

4. In a telephone system, a plurality of normally disconnectedsubscribers lines, means for establishing connection between two of saidlines, a bridge across the calling line, a magnet in series with saidbridge, a second bridge adapted to be placed across the conductors ofthe talking circuit, means controlled by the response of the calledsubscriberfor automatically connecting battery to the mid-point of saidsecond bridge to thereby energize said magnet, and a supervisory slgnalcontrolled by said magnet.

5. In a telephone system, a plurality of normally disconnectedsubscribers lines,v

means for establishing connection between two of said lines, a bridgeacross the calling line, a magnet in series with said bridge, a secondbridge adapted to be placed across the conductors of the talkingcircuit, means controlled by the response of the called subscriber formomentarily connecting battery to the mid-point of said second bridge tothereby energize said magnet, and a signal controlled by said magnet. YSigned by me at Chicago, Illinois, this 16th day of August, 1918.

GEORGE A. YANOCHOWSKI. Signed by me at Hempstead, N. Y., this 13th dayof August, 1918.

' .7 HARRY E. HERSHEY.

